1. Field of the Invention
The present invention relates to a pull printing system, a method for processing print jobs in the pull printing system, a pull printing server, and a computer-readable storage medium for computer program used in the pull printing system.
2. Description of the Related Art
Network printing has attained widespread use in which print jobs are provided to an image forming apparatus such as a printer or a Multi-Functional Peripheral (MFP) via a network. A print job is a print instruction containing information to be printed, and print setting information, e.g., the set of prints, paper size, single-sided/double-sided, monochrome/color, and finishing option. An image forming apparatus executes such a print job.
An example of the network printing is “pull printing” suitable for a network in which a plurality of image forming apparatuses are connected to one another. According to the pull printing, a print job is temporarily stored in a pull printing server, and such a print job is executed (printing is performed) at a time different from a time at which the print job is created (issued). For example, when a user of a personal computer gives a command to print a document, a print job created in the personal computer is transmitted to a pull printing server and is stored therein. Subsequently, the user goes to the site of an image forming apparatus arbitrarily selected by him/her from among a plurality of image forming apparatuses, and instructs the selected image forming apparatus to execute the print job. In response to the instructions, the image forming apparatus pulls the print job out of the pull printing server, and executes the print job. In the pull printing, a user can select an image forming apparatus installed at a place convenient for him/her from among image forming apparatuses installed at places away from one another. Further, in the pull printing, when users share image forming apparatuses installed adjacent to one another, each of the users can select an available image forming apparatus not used by the other users, and use the selected image forming apparatus. In short, the pull printing can provide a just-in-time printing environment.
As for the network printing, a device is disclosed which automatically changes settings for a printer port of a computer from which a print job is issued (see Japanese Laid-open Patent Publication No. 2005-309982). According to the port setting changing device disclosed in the publication, when a printer (previously-used printer) connected to a network is replaced with another printer, a job issued to the previously-used printer is monitored, and port settings for a computer from which the job is issued are changed. This saves a user from having to manually change port settings based on which a transmission destination of a print job in the computer is determined.
In a conventional network printing environment for pull printing, an address of an image forming apparatus executing a print job is registered only in a pull printing server, but is not registered in an information device (typically, a personal computer) functioning as the job issuer to create the print job. Stated differently, the pull printing server is specified as a printer port of the information device that is the job issuer, and a transmission destination of a print job is limited to the pull printing server. Suppose that, in such a case, the pull printing server is brought to a standstill due to some reasons, e.g., for maintenance of the pull printing server or network connection problem. This makes it impossible for the image forming apparatus to perform a printing process, and also impossible for the information device to send a print job.
In order to avoid such a situation, it may be conceived that the information device directly transmits a print job to the image forming apparatus. The following two methods are possible to transmit a print job directly to the image forming apparatus. The first method is applied to a case where a device driver for pull printing server is compliant with the image forming apparatus. The first method is to change a printer port registered in the device driver from the address of the pull printing server to the address of the image forming apparatus. The use of the first method, however, requires a user of the information device to obtain the address of the image forming apparatus, for example, by asking a system administrator about the address thereof. Thus, the user cannot instruct the image forming apparatus to perform a printing process immediately after knowing that the pull printing server halts. As for the second method, a device driver dedicated for image forming apparatus is installed onto the information device in advance. If a print job cannot be transmitted to the pull printing server, then the user manually changes the printer port. According to the second method, a device driver needs to be installed onto the information device in advance, and a user is forced to perform operation for changing the printer port manually.
The operation for changing the printer port manually can be eliminated by using the conventional technique described in Japanese Laid-open Patent Publication No. 2005-309982 to incorporate the port setting changing device described therein into a network. However, this approach needs to install new hardware for monitoring packets flowing through the network, which in turn needs to provide room to install the hardware and to install the necessary wiring.